A procedure that delivers a treatment device through the inside of the lumen of a living body to provide predetermined treatment with respect to a lesion area occurring in biological organs (for example, the blood vessels, the bile ducts, the trachea, the esophagus, the urethra, the nasal cavity, or other organs) has been known. For example, while treating a narrowed area of the blood vessels, a delivery device for delivering a stent (including a drug-eluting stent (DES)) that enlarges the blood vessel wall from the inside thereof, a drug-eluting balloon catheter (DEB), or the like has been used. In addition, in recent years, treatment involving cutting (ablating) the nerve on the inside of the renal artery or the like has been conducted using an ablation device that can be delivered through the inside of the blood vessels as a treatment device, for example.
However, in the above-described procedure, it has been found that the elastic lamina in the intima cracks or fractures due to the treatment device coming into contact with or dilating (the intima of) the thickened blood vessel wall, or inflammation or damage is caused to the blood vessel wall accompanied by the contact of the treatment device. Furthermore, an adverse effect, in which a thrombus is formed inside the blood vessel and causes an embolism (embolus) in the peripheral blood vessel or restenosis is caused in the treated site, also occurs after the treatment.
For this reason, in recent years, a treatment method of coating a substance, such as alginate-catechol, which is gelated (i.e., becomes gelatinous) in a living body, and a coating substance thereof, which are disclosed in U.S. Patent Application Publication No. 2011/0077216 have been proposed. A catechol group is bonded to the blood vessel wall and the catechol groups are crosslinked with each other by adding an oxidant such as periodate to make the coating substance alkaline. Moreover, the alginate-catechol is gelated (becomes gelatinous) in a short period of time. As a result, it is possible to favorably coat the lumen of a living body such as the blood vessels, with the coating substance.
In addition, U.S. Patent Application Publication No. 2011/0077216 discloses a treatment device for coating the above-described coating substance. The device is a tubular shaped member (catheter) that can be delivered through the inside of the blood vessels. The treatment device is configured to have a discharge port on a side surface of a distal portion and to coat the blood vessel wall with the coating substance through the discharge port after the distal portion is delivered to a treatment subject inside the blood vessels by an operator.
However, in the treatment of coating the coating substance inside the blood vessels, when coating a coating substance having a low viscosity, the coating substance after being coated is swept away by the blood. For this reason, during the coating, it is preferable to coat a coating substance having a high viscosity. However, in this case, discharge resistance of the coating substance increases and it is difficult to precisely coat a desired area to be treated, with the coating substance by simply coating onto the inner surface of the blood vessels through the discharge port of the treatment device as disclosed in U.S. Patent Application Publication No. 2011/0077216.
In addition, the coating substance having a high viscosity is affected by flow of blood (blood flow) after being coated onto the blood vessels. As a result, there is a possibility that the shape of the coating layer is easily changed to an unintended shape, and thereby the ability of treating the treatment subject deteriorates. For example, it is considered that while the gelation reaction is completed after the coating, if the gelation completes in a state in which a distal section (outlet side of the blood flow) of the coating layer swells by shear stress due to the blood flow causing a step in the coating layer, the step promotes formation of a thrombus by causing disturbance of the blood flow or retention of blood, and as a result, the ability of the treatment rather deteriorates.